POV: HOW TO PLOT SUN'S LOPs

Plotting a Line of Position (LOP) of the Sun in celestial navigation is a core skill. It comes from your computed altitude (Hc) and observed altitude (Ho) using a sextant. Here’s a clear step-by-step guide you can follow onboard or in exams. ⸻ 🌞 1. What You Need • Sextant altitude of the Sun (Hs → Ho after corrections) • Accurate time (UTC) • Your DR (Dead Reckoning) position (Lat & Long) • Nautical Almanac + Sight Reduction Tables (or calculator) ⸻ 📐 2. Compute Your Sight (Celestial Computation) After calculations, you will get: • Hc = Computed altitude • Zn = True azimuth of the Sun • Intercept (a) = Ho − Hc 👉 Interpret intercept: • If Ho Hc → “Towards” (T) • If Ho Hc → “Away” (A) ⸻ 🗺️ 3. Plot the Assumed Position (AP) • Choose an Assumed Position (AP) close to your DR • Plot it on the chart (or plotting sheet) ⸻ 🧭 4. Draw the Azimuth Line (Zn) • From the AP, draw a line in the direction of Zn (true bearing of the Sun) ⸻ 📏 5. Measure the Intercept • Convert intercept into nautical miles: • 1 minute of arc = 1 nautical mile • From AP, measure along the azimuth line: • Towards (T) → move toward the Sun • Away (A) → move away from the Sun Mark this point clearly. ⸻ 📉 6. Draw the Line of Position (LOP) • At the intercept point, draw a line perpendicular (90°) to the azimuth line 👉 This perpendicular line is your LOP ⸻ ✳️ 7. Label the LOP Include: • Time of observation • Body observed (Sun) • Intercept & direction (e.g., 5 NM T) ⸻ 📍 8. Fix Your Position (if multiple sights) • Take another sight (later or different body) • Plot second LOP • Intersection = your position fix Thank you! #ConcernedProfessor 📸 D/CDT MABANSAG #fyp #fyppage #Seafarer #SEAMAN #lopplotting